Conclusion
Early apoptosis of monocytes upon presentation of clinical signs of sepsis is connected to a favourable outcome. These findings are of particular importance for the patient with septic shock, where they might constitute a mechanism of pathogenesis.
Methods
Blood monocytes were isolated from 90 patients with septic syndrome due to ventilator-associated pneumonia on days 1, 3, 5 and 7 from the initiation of symptoms. Apoptosis was defined after incubation with annexin-V-fluorescein isothiocyanate and propidium iodine and reading by a flow cytometer. The function of first-day monocytes was evaluated from the concentrations of tumour necrosis factor alpha (TNFalpha) and IL-6 in supernatants of cell cultures after triggering with endotoxins. TNFalpha, IL-6 and IL-8 were estimated in serum by an enzyme immunoassay.
Results
Mortality rates of patients with apoptosis < or =50% compared with patients with apoptosis >50% were 49.12% and 15.15%, respectively (P < 0.0001). Kaplan-Meier analysis showed a 28-day survival benefit in patients with septic shock and monocyte apoptosis >50% compared with those patients with apoptosis < or =50% (P = 0.0032). Production of IL-6 by monocytes on the first day by patients with apoptosis < or =50% was similar compared with monocytes isolated from healthy controls. Serum concentrations of TNFalpha were higher in patients with monocyte apoptosis < or =50% and septic shock compared with patients with apoptosis >50% on day 7; similar findings occurred for serum IL-6 on days 1 and 7 and for serum IL-8 on days 1 and 5.